Karnataka J. Agric. Sci.,24 (1) : (39-44) 2011

Potassium and human nutrition: The soil-plant-human continuum K. BHASKARACHARY Food Chemistry Division, National Institute of Nutrition, Hyderabad-500007, India Email: [email protected] (Received: November, 2010) Abstract : Most potassium occurs in the earth's crust as minerals, such as feldspars and clays. Potassium ranks seventh in order of abundance in the earth's crust. As rocks slowly disintegrate, potassium is released, but the rate of release is too slow to provide the large amounts of this essential nutrient required by crops. Humans obtain the majority of their potassium either directly from plants or indirectly through the animal products in their diet. Thus potassium is considered as an indispensable macro element for sustenance of life on the earth. Starting from soil health which is essential for plant growth and subsequently the health of animals and humans, potassium has important role to play. The current review covers the various roles potassium play in soil, plant and human health. In view of the recent interest generated on the new roles of potassium in human health i.e. control of hyper tension etc., particularly emphasis has been placed on the clinical significance and cellular functions of this electrolyte in human health and disease. Key words: Potassium, soil health, animal health, human health, clinical significance

Introduction

resistant to disease attack. Sound fertility management and fertilization practices provide assurance that stress induced by K defciency is not a factor in crop production (Cook and Duff, 1976). Several factors influence the effectiveness of K fertilizer in reducing crop stress and disease incidence. Of all the nutrients essential for plant growth and function, potassium (K) is most often associated with reducing disease severity. It should be recognized, however, that K does not work alone. The healthiest, most profitable crops are produced with balanced fertility management practices that minimize nutrient stress throughout the growing season. Its presence is of great importance for soil health, plant growth and animal nutrition. Although it is soluble in water, little is lost from undisturbed soils because as it is released from dead plants and animal excrements, it quickly becomes strongly bound to clay particles, and it is retained ready to be re-adsorbed by the roots of other plants. As such, the element is required in relatively large proportions by the growing plant. The consequences of low potassium levels are apparent in a variety of symptoms such as restricted growth, reduced flowering, lower yields and lower quality produce. A high water soluble level of potassium cause damage to germinating seeds and inhibits the uptake of other minerals, and reduces the quality of the crop.

Potassium is a major constituent in all living cells and, potassium (K) is essential nutrient required in large amounts by plants, animals and humans (Hamdallah, 2004). Most potassium occurs in the earth’s crust as mineral, such as feldspars and clays. Potassium ranks seventh in order  of abundance in the earth’s crust. As rocks slowly disintegrate, potassium is released, but the rate of release is too slow to provide the large amounts of this essential nutrient required by crops. Humans obtain the majority of their potassium either directly from plants or indirectly through the animal products in their diet. Potassium is a key element for crops / plant growth. Therefore, the intricate relationship between plant nutrition, animal nutrition and the impact on food chain for human is very much essential. Potassium and soil health Soil may be defined as a thin layer of earth’s crust which serves as a natural medium for growth of plants. Term, soil, is used to describe agriculture and garden life. Soil is the principal attribute and supports life on earth. Soil has four main components such as minerals, organic matter, air and water. A fertile soil can be described as it is rich in nutrients necessary for basic plant nutrition, including nitrogen, phosphorus and potassium. Among the minerals potassium stands as macro element and very much essential for plant growth. Heavy crop production rapidly depletes soils of potassium, and agricultural fertilizers consume 93% of the potassium chemical production of the modern world economy. Maintenance of adequate potassium is therefore, essential for both organic and conventional crop production. Disease resistance in crops is genetically controlled. However, natural disease resistance mechanisms can be enhanced by plant nutrients. Potassium deficiency symptoms such as thin cell walls, weakened stalks and stems, smaller and shorter roots, sugar accumulation in the leaves, and accumulation of unused nitrogen (N) encourage disease infection. Each of these reduce the ability of the plant to resist entry and infection by fungal, bacterial and viral disease organisms. A healthy plant, free from stress, is much more

Land is the starting point Because, soils are the natural base for growing crops and raising animals; then it is imperative that its fertility will impose the quality and mineral content of such agricultural products. Therefore, nutrient deficiencies in soils are reflected not only on crop yields, but also on their contents of mineral nutrients. Food stuffs and animal feeds, containing low amounts of nutrients, would lead to mineral deficiencies in animals and humans also. There were rare occasions, scientists working on various disciplines like (soil science/plant nutrition, human nutrition, veterinary/animal nutrition, as well as, medical sciences and human nutrition), would convene to study the inter-related problems and concerns of these domains. Only a multidisciplinary approach to study those areas would produce 39

Karnataka J. Agric. Sci.,24 (1) : 2011 the help of potassium as they develop resistance against drought, variations in temperatures and plant diseases (Nus and Sandburg, 1991). This element also helps the plant to absorb more water and improve the health of the plants. Together with nitrogen and phosphorous, potassium is one of the essential macro minerals for plant survival.

plausible remedies to the nutrients imbalance and deficiencies in the human diet, that can be best offset by treating those deficiencies in plants and consequently in animals and finally on human population. Potassium release from soil minerals The most common mineral sources of K in soils are feldspars and micas, soil minerals remaining from the primary parent material. Weathering of these primary minerals produces a range of secondary minerals that may also serve as a source of potassium in soil. These minerals include micaceous clays such as illite and vermiculite. Crushed rocks and minerals have been evaluated as potassium sources in many field and greenhouse experiments. In general, plants are able to gain a very limited amount of potassium from minerals applied as biotite, phlogopite, muscovite, and nepheline. Feldspar potassium is not plant available without additional treatment or weathering. The rate of K release from minerals is influenced by factors such as soil pH, temperature, moisture, microbial activity, the reactive surface area, and the type of vegetation. Therefore, a mineral that is somewhat effective as a K source in one condition may be ineffective in another environment. Some soil minerals may act as a sink for removing K from solution. When K is adsorbed in the interlayer sites of illite, vermiculite and other smectite clays, the clay layers collapse and trap the K within the mineral lattice. This fixation process is relatively fast, while the release of this interlayer K is very slow. Non-exchangeable K should not be confused with mineral K, since non-exchangeable K is held between adjacent tetrahedral layers of clay, instead of being covalently bonded in mineral crystal structures.

Potassium and human health Potassium, is the third most abundant mineral in human body, identified as the synonym for health insurer. Potassium is the principal positively charged ion (cation) in the fluid inside cells, while sodium is the principal cation in the fluid outside cells. It is one of the substances found in foods that maintain the body’s internal balance of fluids and chemicals. More than 98% of the body’s potassium is intracellular; measuring it from a blood sample is relatively insensitive, with small fluctuations in the blood corresponding to very large changes in the total bodily reservoir of potassium. Potassium is found in especially high concentrations within plant cells, and in a mixed diet, it is most highly concentrated in fruits. It contains qualities for maintaining a high level of human well-being and a cheerful lifestyle (Heyka, 2009). Apart from acting as an electrolyte, this mineral is required for keeping heart, brain, kidney, muscle tissues and other important organs of human body in good condition. Elevations or deficiencies of this important mineral can cause problems and, in the extreme, even death. Maintaining consistent levels of potassium in the blood and cells is vital to body function. Therefore, there is no way one should overlook the inclusion of potassium in routine diet plan (O’Shaughnessy, 2006). The health benefits of potassium includes blood pressure, anxiety, stress, muscular strength, metabolism, heart strokes, kidney disorders, water balance, electrolytic functions, nervous system and many other health benefits are well documented (Poirier, 1984; Sacks et al., 1998). Potassium chloride is the main compound of this mineral amongst others. It works in association with sodium to  perform  a  number  of  critical  body  tasks. Potassium may be looked upon as an essential health nutrient, due to following health benefits: Brain stroke: Potassium plays an important role in keeping the working of brain in normal state. It is of great importance in preventing the occurrence of stroke in human brain (Iso et al., 1999). Though, the exact mechanism of potassium involvement in brain stoke is not known, Potassium decreases vascular smooth muscle cell proliferation in the small arteries of the brain and two-pore domain potassium channel family (K2P channels) could be shown to be involved in mechanisms contributing to neuronal damage after cerebral ischemia (Ehling et al., 2010). Low blood sugar: Decrease in potassium level causes a drop in blood sugar level. Decrease in blood sugar level causes sweating, headache, weakness, trembling and nervousness. Intake of potassium chloride and sodium provides immediate relief from such situation (Apstein, 1998; Apstein and Opie, 1999). Muscle disorders: Potassium  plays  an  important  role  in regular muscle contraction. Right concentration of potassium,

Potassium balance in soil Farming always leads to removal of potassium and additional loss of potassium through leaching and runoff is inevitable, the potential of a cropping management system to replenish the potassium reserve is important. The demand for K by various crops has been well established by measuring the potassium concentration in the harvested portion of the crop. However, much less attention has been paid to the rate at which K must be supplied to growing plants. Both the total amount required (quantity) and the rate of supply frequency are equally important. This concept is important for all crop growth, but requires special attention when using low-solubility nutrient sources that may provide an adequate amount of total K, but not at a rate sufficiently rapid to meet peak-demand periods of plant growth. Potassium and plant growth Potassium (K) is often described as the “quality nutrient” for crop production. With a shortage of K, photosynthesis, respiration, translocation, and a number of enzyme systems don’t function very well. The result can be a reduction of plant growth and, often, of crop quality. Its primary function in the plant is its role in the maintenance of osmotic pressure and cell size, thereby influencing photosynthesis and energy production as well as stomata opening and carbon dioxide supply, plant turgor and translocation of nutrients. Capacity of crops is increase with 40

Potassium and human nutrition: The soil-plant-human continuum

is required for the regular contraction and relaxation of the muscle. Most of the potassium ions of the human body are present inside the muscle cells. It maintains muscle function and optimal nerve. A large part of the weakened connective tissue from a potassium deficiency is manifesting itself by virtue of the indirect effect a continuing potassium deficiency is having on the the copper metabolism especially as it pertains to the copper catalyzed lysyl oxidase enzyme. Cramps: Muscle  cramps  result  due  to  low  level of potassium in the blood, a condition called as hypokalemia. Intake of a banana everyday prevents muscle cramp. Bananas are rich in potassium content. Brain function: Potassium  channels  play  a  key  role  in maintaining the electrical conductivity of brain and affect the brain function. High levels of extracellular K+ ensure proper development and prolong survival of cerebellar granule neurons. It is also involved in higher brain function like memory and learning. In addition to it, serious ailments like epilepsy are related to the functioning of potassium channels. When a neuron decides to transmit signal, the cell wall suddenly becomes permeable to sodium ions, and sodium ions near the cell wall suddenly move into the cell, followed a microsecond later by a flow of thousands of potassium ions in the opposite direction (Fuhrman, 1967). This change in permeability shoots down the nerve fiber as a wave at about 100 meters per second powered by 1/10 of a volt of concentration differential (Baker, 1966). Blood pressure: Potassium is helpful in reversing the role of sodium in unbalancing the normal blood pressure (Brancati et al. 1996; Cappuccio and MacGregor, 1991). Thus, it acts as a vital component, which maintains the normality of blood pressure in human body. This further abolishes the possibilities of heart diseases and hypertension (Burgess et al., 1999; Pikilidou et al., 2007). Regulation of blood pressure is an important function of this mineral (Appel, 1999; Houston, 2007). The mechanism of the antihypertensive effect is not well defined. Variations in serum potassium within the physiologic range may directly affect vascular smooth muscle tone. Potassium may also influence the regulation of blood pressure through effects on sodium handling, aldosterone secretion, the renin/ angiotensin system, renal kallikrein, eicosanoids, and atrial natriuretic peptide (Smith et al., 1992). The sodium pump probably operates at two different sites, one affected by aldosterone, the other by vasopressin (a protein peptide hormone, used to retain water by humans), and using a different energy system (Sharp, 1966). The switch to a rheostat that modulates the balance of salt and potassium in the kidney, thereby raising or lowering blood pressure.  Anxiety and stress: Potassium is of great importance for people suffering from undesirable mental states like anxiety and stress. It is considered as a perfect stress buster and thus, it ensures efficient mental performance of human body. Muscular strength: This  is  in  fact,  one  of  the  most appreciable benefits of potassium, as it ensures proper growth of muscle tissues and proper utilization of energy released during metabolism to add significant worth to muscular strength (Singh et al. 1999). The muscles, together with cardiac muscle, are prone to paralysis due to deficiency of potassium in diet (Matsui et

al., 2006; Young et al., 1995). A study conducted on a ninemonth infant, weighing 9.8 kg with hypotonia secondary to acute hypokalaemia (1.0 mmol/l), muscle strength was improved as the serum potassium was increased by supplementation (Ried et al., 1997).  Metabolism: It  assists  in  metabolic  process  of  various nutrients like fats, proteins and carbohydrates. Thus, potassium is  of  great  value  in  extracting  the  energy  out  of nutrients consumed by man (Blevins, 1985). In the cytoplasm, K has an important role in providing the correct ionic environment for metabolic processes. The ionic requirements of protein synthesis seem to be particularly important in determining the composition of the cytoplasm. Potassium is known to be the activator for several enzyme systems (Suelter, 1970). Since only minute amounts are needed for most of them, there could never be a deficiency which would inactivate the majority of them. Heart and kidney disorders: The  health  benefits of potassium ensure good health for heart as well as kidneys (Kendler, 1997). Several studies suggest that potassium deficiency can contribute to diastolic dysfunction and possibly to systolic dysfunction as well. One mechanism by which potassium might help prevent heart failure is by inhibiting cardiac NADPH oxidase activity, thereby decreasing oxidative stress. High salt intake significantly increased blood pressure, impaired left ventricular relaxation, and increased the activity of IVADPH oxidase in cardiac tissue. High potassium intake improved left ventricular relaxation and reversed the elevation of NADPH oxidase activity, even though blood pressure remained high. It plays an irreplaceable role in regulating the functions of potassium. Apart from this, this mineral assists kidneys to remove waste by the process of excretion (Rafferty and Heaney, 2008). However, it is strictly advisable to consult your doctor to get recommendation about dosage. Abnormally high calcium in the urine increases the risk of developing kidney stones. Increasing dietary potassium intake has been found to decrease urinary calcium excretion, thereby potentially preventing kidney stone formation. Water balance: Potassium has another significant role to play in maintaining the desirable water balance in human body. There are different types of cells, which require having proper water balance for proper functioning and potassium aids these cells in regulating this balance. Potassium also regulates the acid-base balance in the blood and tissues. During a potassium deficiency, potassium migrates out of the cell and causes the cell fluid to become acidic (lower pH) (Davis, 1970). This is probably related to the circumstance that sodium does not take up the full slack, coupled with a rise in weak base forming anions such as positively charged amino acids. The buffering action of the negatively charged ions of weak acid forming anions such as phosphate is the chief innate regulator of the acid - base balance. Electrolyte: Potassium  plays  the  significant  role  as  an electrolyte in human body. It helps in regulating the level of fluids in human body and thus performs a number of critical body functions (Matsumura et al., 2000). Nervous system: Potassium helps in boosting the spirit of 41

Karnataka J. Agric. Sci.,24 (1) : 2011 nerve reflexes to transmit message from one body part to another. This in turn helps in muscle contraction to perform various activities every day. Rapid changes in extracellular K+ concentration in the mammalian CNS are counteracted by simple passive diffusion as well as by cellular mechanisms of K+ clearance. Buffering of K+ can occur via glial or neuronal uptake of K+ ions through transporters or K+-selective channels. A specialized form of spatial buffering named K+ siphoning takes place in the vertebrate retina, where glial Muller cells express inwardly rectifying K+ channels (Kir channels) positioned in the membrane domains near to the vitreous humor and blood vessels thereby controlling blood pressure. They suggest a close physical and functional relationship between Kir and water channels in glial cells (Koufi and Newman, 2004).

Table 1. High potassium foods (>450 mg per serving) Food Measure Potassium (mg) Avocados 3 oz. 540 Bananas 1 medium 467 Beets, cooked 1 cup 519 Beet greens, cooked 1 cup 1,309 Broccoli 1 cup 505 Brussels Sprouts, cooked 1 cup 504 Cantaloupe 1 cup 495 Chick Peas, cooked 1 cup 477 Cod 4 oz. 585 Halibut 4 oz. 653 Kidney Beans, cooked 1 cup 713 Lima Beans, cooked 1 cup 955 Lentils, cooked 1 cup 731 Papaya 1 medium 781 Raisins 1/2 cup 544 Soybeans 1 cup 886 Spinach, cooked 1 cup 839 Swiss Chard, cooked 1 cup 961 Trout 4 oz. 500 Tuna 4 oz. 645 White Beans, cooked 1 cup 1,189

Balancing of potassium in body “Hyperkalemia” is when there is too much potassium in the blood. Older people are at a greater risk of hyperkalemia because, as people age, the kidneys are less efficient at eliminating potassium. Also, many medications associated with the elderly can affect their potassium levels. Too much potassium in the blood can cause diarrhea, nausea, vomiting and ulcers. When there is too little potassium in the blood due to loss through urination or in the intestines this condition is called “hypokalemia”. Hypokalemia is rarely caused by not enough potassium in the diet. Symptoms of hypokalemia are weakness, fatigue, stomach issues, muscle cramps and irregular heartbeat. Hypokalemia can become life-threatening, so it is important for it to be treated by a doctor.

Table 2. Moderately high potassium foods (225 - 450 mg per serving) Food Measurement Potassium (mg) Almonds 2 oz. 412 Carrots, raw 1 cup 394 Celery, raw 1 cup 344 Green beans, cooked 1 cup 374 Kale, cooked 1 cup 296 Kiwi 1 medium 252 Milk, nonfat 1 cup 376 Mustard greens, cooked 1 cup 283 Orange 1 medium 237 Peanuts 2 oz. 374 Salmon 4 oz. 425 Tomato, ripe 1 cup 400 Turnip greens, cooked 1 cup 292

Symptoms of deficiency A diet that does not include enough potassium rich foods or dietary supplements will soon lead to health complications. Symptoms of a deficiency of potassium in the body include water retention, heart arrhythmias, continual thirst, high blood pressure, nerve and muscle dysfunction and vomiting. The vomiting will lead to a further deficiency in the mineral. These symptoms, affecting numerous body functions are caused by the electrolyte imbalance brought on by potassium deficiency. Dietary sources of potassium

Potassium supplementation: Several potassium supplements are in the market, including potassium acetate, potassium bicarbonate, potassium citrate, potassium chloride, and

Potassium is found in a wide range of foods. Potassium rich foods are easy to find, relatively inexpensive, and are probably already a part of your regular diet. The best dietary sources of potassium are fresh unprocessed foods. Many fruits and vegetables are high in potassium and low in sodium and helps preventing hypertension (Dickinson et al., 2006; Suter, 1998).

Table 3. Recommend K intake levels Age 0-6 months: 6-12 months: 1-3 years: 4-8 years: 9-13 years: 14-18 years: 19-30 years: 31-50 years: 51+ years: Pregnant women: Lactating women:

Dosage, intake, recommended daily allowance (RDA)  Because deficiency of potassium is rarely observed, there is no recommended daily allowance for potassium. It is usually easy to obtain adequate potassium in a normal balanced diet and this helps to overcome blood pressure and hypertension (Hermansen, 2000; Myers and Champagne 2007). In 2004, the Institute of Medicine at the National Academy of Sciences (Maryland, USA) issued new Adequate Intake (AI) levels for potassium. The recommendations are as follows: 42

K level 400 mg 700 mg 3.5 g 3.8 g 4.5 g 4.5 g 4.7 g 4.7 g 4.7 g 4.7 g 5.1 g

Potassium and human nutrition: The soil-plant-human continuum..................

potassium gluconate. They are available as tablets, capsules, effervescent tablets, powders, and liquids. Potassium is also found in combination with multivitamins. Potassium supplements, other than the small amount included in a multivitamin, should be taken only under your doctor’s supervision, more specifically in case of children.

heart rhythm may occur. People with hyperkalemia or kidney disease should not take potassium supplements (Chiu et al., 1997; Whelton et al., 1990). People who take ACE inhibitors (Ray et al., 1999), potassium-sparing diuretics, or the antibiotic trimethoprim (Perazella, 2000; Perazella and Mahnensmith, 1997) and sulfamethoxazole (Bactrim, Septra) should not take potassium (Alappan et al. 1996; Newnham, 2001).

Precautions

Conclusions

Because of the potential for side effects and interactions with medications, one should take dietary supplements only under the supervision of a health care provider (Howes, 1995). Side effects include diarrhea, stomach irritation, and nausea. At higher doses, muscle weakness, slowed heart rate, and abnormal

Potassium is an essential element for the health of soil, plant and humans. Though, the recommended dietary allowances for humans are not given, it is essential to maintain the normal potassium levels in the body for various physiological functions.

References Alappan, R., Perazella, M.A., and Buller, G.K., 1996, Hyperkalemia in hospitalized patients treated with trimethoprimsulfamethoxazole. Ann.  Int.  Med., 124(3):  316-320.

Dickinson, H.O., Nicolson, D.J., Campbell, F., Beyer, F.R. and Mason, J., 2006, Potassium supplementation for the management of primary hypertension in adults. Cochrane Database Syst. Rev., 19(3): 4641.

Appel, L. J.,1999, Nonpharmacologic therapies that reduce blood pressure: a fresh perspective. Clin. Cardiol., 22(3): III1-III5.

Ehling. P., Bittner, S., Bobak, N., Schwarz, T., Wiendl, H., Budde, T., Kleinschnitz, C. and Meuth, S.G., 2010, Two pore domain potassium channels in cerebral ischemia: a focus on K2P9.1 (TASK3, KCNK9). Exp. Transl. Stroke Med., 2(1):14.

Apstein, C., 1998, Glucose-Insulin-Potassium for acute myocardial infraction: remarkable results from a new prospective, randomized trial. Circ., 98: 2223-2226.

Fuhrman, F.A., 1967, Tetrodotoxin. Scientific American, 217: 60-71.

Apstein, C.S. and Opie, L.H., 1999, Glucose-insulin-potassium (GIK) for acute myocardial infarction: a negative study with a positive value. Cardiovasc. Drugs Ther., 13(3): 185-189.

Hamdallah, G., 2004, Plant, Animal and Human Nutrition: An Intricate Relationship. Expert Consultation on Land Degradation and Plant, Animal and Human Nutrition, ACSAD, Damascus, Syria, 20-23 September, 2003.

Baker, P.F., 1966, The nerve axon. Scientific American, 214:74. Blevins, D.G., 1985, Role of potassium in protein metabolism. In: Potassium in Agriculture. Ed. Munson, R.D., Amer. Soc. Agron., Madison, Wiseonsin., p.413-424.

Hermansen, K., 2000, Diet, blood pressure and hypertension. British J. Nutr., 83(1): S113-119.

Brancati, F.L., Appel, L.J., Seidler, A.J. and Whelton, P.K., 1996, Effect of potassium supplementation on blood pressure in African Americans on a low-potassium diet. Arch. Intern. Med., 156: 61-72.

Heyka, R., 1999, Lifestyle management and prevention of hypertension. In: Lifestyle Medicine. Ed. Rippe. J. 1 st ed. Malden, Mass: Blackwell Science, pp.109-119. Houston, M.C., 2007, Treatment of hypertension with nutraceuticals, vitamins, antioxidants and minerals. Expert Rev Cardiovasc. Ther., 5(4):681-91.

Burgess, E., Lewanczuk, R. and Bollim, P., 1999, Lifestyle modifications to prevent and control hypertension. 6. Recommendations on potassium, magnesium and calcium. Canadian Hypertension Society, Canadian Coalition for High Blood Pressure Prevention and Control, Laboratory Centre for Disease Control at Health Canada, Heart and Stroke Foundation of Canada. CMAJ., 160(9): S35-S45.

Howes, L.G., 1995, Which drugs affect potassium? Drug Saf., 12(4): 240-244. Iso, H., Stampfer, M.J. and Manson, J.E., 1999, Prospective study of calcium, potassium, and magnesium intake and risk of stroke in women. Stroke, 30(9): 1772-1779.

Cappuccio, E.P. and MacGregor, G.A., 1991, Does potassium supplementation lower blood pressure ? A meta-analysis of published trials. J. Hypertens., 9: 465-473.

Kendler, B.S., 1997, Recent nutritional approaches to the prevention and therapy of cardiovascular disease. Prog. Cardiovasc. Nurs., 12(3): 3-23.

Cook, T.W. and Duff. D.T., 1976, Effects of K fertilizers on freezing tolerance and carbohydrate content of Festuca arundinacea Schreb. maintained as turf. Agron. J., 68: 116-119.

Kofuji, P. and Newman, E.A., 2004, Potassium buffering in the central nervous system. Neuroscience, 129: 1045-1056.

Chiu, T.F., Bullard, M.J., Chen, J.C., Liaw, S.J. and Ng, C.J., 1997, Rapid life-threatening hyperkalemia after addition of amiloride HCL hydrochlorothiazide to angiotensin-converting enzyme inhibitor therapy. Ann. Emerg. Med., 30(5): 612-615.

Matsui. H., Shimosawa, T., Uetake, Y., Wang, H., Ogura, S. and Kaneko, T., 2006, Protective effect of potassium against the hypertensive cardiac dysfunction: association with reactive oxygen species reduction. Hypertension, 48(2): 225-31.

Davis, W.H., 1970, Does potassium deficiency hold a clue to metabolic disorders associated with liability to coronary heart disease? South African Med. J., 44: 1297.

Matsumura, M., Nakashima, A. and Tofuku, Y., 2000, Electrolyte disorders following massive insulin overdose in a patient with type 2 diabetes. Intern Med., 39(1): 55-57. 43

Karnataka J. Agric. Sci.,24 (1) : 2011 Myers, V. H. and Champagne, C. M., 2007, Nutritional effects on blood pressure. Curr. Opin. Lipidol., 18(1): 20-24.

Reid A.W., Anderson,  B.J., Futter,  M.E.  and Holford,  N.H.,  1997, Relationship of muscle strength to potassium concentration in a hypokalaemic infant. Anaesth. Intensive Care, 25(5): 525527.

Newnham, D. M., 2001, Asthma medications and their potential adverse effects in the elderly: recommendations for prescribing. Drug Saf., 24(14): 1065-1080. Nus, J. L. and Sandburg, M. A., 1991, The role of potassium in water stress. Grounds Maintenance, 26(5): 58-60.

Sacks, F.M., Willett, W. C. and Smith, A., 1998, Effect on blood pressure of potassium, calcium and magnesium in women with low habitual intake. Hypertens, 31(1):131-138.

O’Shaughnessy, K.M., 2006, Role of diet in hypertension management. Curr.  Hypertens.  Rep.,  8(4):  292-7.

Sharp, G.U.G. and Leaf, A., 1966, Mechanism of action of aldosterone. Phys. Rev., 46: 593.

Perazella, M.A., 2000, Trimethoprim-induced hyperkalemia: clinical data, mechanism, prevention and management. Drug Saf., 22(3): 227-236.

Singh, R.B., Singh, N.K., Niaz, M.A. and Sharma, J.P., 1996, Effect of treatment with magnesium and potassium on mortality and reinfarction rate of patients with suspected acute myocardial infarction. Int. J. Clin. Pharmacol. Ther., 34: 219-225.

Perazella, M. and Mahnensmith, R., 1997, Hyperkalemia in the elderly. J.  Gen.   Intern.  Med., 12: 646-656.

Smith, S. R., Klotman P. E. and Svetkey, L.P., 1992, Potassium chloride lowers blood pressure and causes natriuresis in older patients with hypertension. J. American Soc. Nephrol., 2: 1302-1309.

Pikilidou, M. I., Lasaridis, A.N., Sarafidis, P. A., Tziolas, I.M., Zebekakis, P. E., Dombros, N. V. and Giannoulis, E., 2007, Blood pressure and serum potassium levels in hypertensive patients receiving or not receiving antihypertensive treatment. Clin.  Exp.  Hypertens.,  29(8):  563-73.

Suelter, C.H., 1970, Enzymes activated by monovalent cations. Science, 168: 789-795

Poirier, T.I., 1984, Reversible renal failure associated with ibuprofen: case report and review of the literature. Drug Intel. Clin. Pharm., 18(1): 27-32.

Suter, P.M., 1998, Potassium and Hypertension. Nutr. Rev., 56: 151133.

Rafferty, K. and Heaney, R.P., 2008, Nutrient effects on the calcium economy: emphasizing the potassium controversy. J. Nutr., 138(1): 166S-171S.

Whelton, A., Stout, R.L., Spilman, P.S. and Klassen, D.K., 1990, Renal effects of ibuprofen, piroxicam, and sulindac in patients with asymptomatic renal failure. A prospective, randomized, crossover comparison. Ann. Intern. Med., 112(8): 568-576.

Ray, K., Dorman, S. and Watson, R., 1999, Severe hyperkalemia due to the concomitant use of salt substitutes and ACE inhibitors in hypertension: a potentially life threatening interaction. J. Hum. Hypertens., 13(10): 717-720.

Young, D.B., Lin, H. and McCabe, R.D., 1995, Potassium’s cardiovascular protective mechanisms. American J. Physiol., 268(2): R825-R837.

44